All manner and variety of absorbent articles configured for the absorption of body fluids such as menses, urine, and feces are, of course, well known. Absorbent articles, particularly sanitary napkins, having wings or flaps are disclosed in the literature and are available in the marketplace.
Generally, the flaps extend laterally from a central absorbent means and are intended to be folded around the edges of the wearer's panties in the crotch region. Thus, the flaps are disposed between the edges of the wearer's panties in the crotch region and the wearer's thighs. Commonly, the flaps are provided with an attachment means for affixing the flaps to the underside of the wearer's panties.
The flaps serve at least two purposes. First, the flaps prevent exudates which otherwise would soil the edges of the wearer's panties from doing such. Second, the flaps help stabilize the napkin from shifting out of place, especially when the flaps are affixed to the underside of the panties.
Sanitary napkins having flaps of the various types are disclosed in U.S. Pat. No. 4,687,478, entitled “Shaped Sanitary Napkin With Flaps”, which issued to Van Tilburg on Aug. 18, 1987, U.S. Pat. No. 4,608,047, entitled “Sanitary Napkin Attachment Means”, which issued to Mattingly on Aug. 26, 1986, U.S. Pat. No. 4,589,876, entitled “Sanitary Napkin”, which issued to Van Tilburg on May 20, 1986, U.S. Pat. No. 4,285,343, entitled “Sanitary Napkin”, which issued to McNair on Aug. 25, 1981, U.S. Pat. No. 3,397,697, entitled “Disposable Sanitary Shield For Undergarments”, which issued to Rickard on Aug. 20, 1968, and U.S. Pat. No. 2,787,271, entitled “Sanitary Napkin”, which issued to Clark on Apr. 2, 1957. Often flaps are coated with an adhesive to assist in fixing the absorbent article to the wearer's panty.
When the flaps are folded down along the edges of the wearer's panties, stresses are created in the flaps. The stresses are especially high along the bending line at the edges of the wearer's panties where the flaps are bent from the bodyside of the panty to the underside of the panty. These stresses are caused by fitting a flap around the curved outline of a panty crotch. These stresses are magnified when a wearer sits or crouches because the edges of the panties are pulled outward against the flaps thus increasing the forces against this bending line. When the stresses become too high, the flaps may become detached from the panty and some portion of the aforementioned benefits of the flaps may be lost. In addition, even if the stresses are not sufficient to detach the flaps, they may still be sufficient to cause the flaps to bunch longitudinally inward. This effectively reduces the size of the flaps and the area of the wearer's undergarments that the flaps are able to cover. One approach to relieving these stresses is to provide flaps that have stress release means for relieving the stresses that develop in the flaps.
While sanitary napkins having flaps that include stress release means are viewed as providing better fit with the panty and better protection against soiling as compared to sanitary napkins without stress release means in the flaps, sanitary napkins having flaps that include stress release means commonly experience problems that keep them from being optimally effective. One problem is that when the wearer applies forces to the flaps to fold the flaps down and under the wearer's undergarment, individual flaps can fail to fold as a single unit. As a result, the portion of a flap that is folded adheres to the wearer's panty. The wearer then folds the remainder of the flap and attaches the flap to the panty. This multi-step process that is sometimes used by wearer's to attach a single flap to the wearer's panty can result in bunching and wadding of the flap, improper location of the absorbent article relative to the wearer's body, and failure of the flap to securely attach the absorbent article to the wearer's panty.
One possible solution to the problem of flaps failing to fold as a single unit is to make the flap out of a stiffer material. However, this solution may not be preferred because the absorbent article is worn in the crotch area of the wearer and as the wearer moves, the wearer's panty to which the absorbent article is attached moves and the absorbent article itself moves. Furthermore, the absorbent article can be in contact with the wearer's body and affect how the wearer's panty fits the wearer's body. Given the location where the wearer wears the absorbent article, more flexible materials are likely preferred by wearers over rigid inflexible materials because these materials may have less effect on the fit of the wearer's panty and can be more comfortable when worn in the crotch of the wearer. Additionally, using a stiffer material to construct the flaps is counter to the need to have flap materials that have stress release means to relieve the stress from folding the flap beneath the panty.
Ideally, the flaps could be relatively stiffer in particular directions so as to allow each flap to fold as a single unit when the user applies force to fold the wing yet still be relatively less stiff in other directions so as to allow stresses developed from folding the flap beneath the panty to be relieved and allow the absorbent article to be worn comfortably.
Another complicating problem is that the shape of the panty line in the wearer's crotch is often curved. Moreover, the curvature of the panty line in the wearer's crotch may vary from the portion of the panty generally oriented towards the wearer's front and the portion of the panty generally oriented towards the wearer's rear. Thus, as the flap of a sanitary napkin is folded underneath the wearer's panty, non-uniform stresses can develop along the bending line of the flap. The non-uniform stresses can impede the bending line of the flap in the engaged position from conforming to the panty line in the wearer's crotch region and result in the same problems as above including failure of the flap to attach to the wearer's panty, bunching and wadding of the flap, and an improperly located sanitary napkin.
Thus, there is a continuing unaddressed need for flaps that each fold as a single unit and have the desired ability to relieve stresses developed as a result of folding the flap beneath the wearer's panty.
Furthermore, there is a continuing unaddressed need for flaps having relatively less stiff areas that are oriented with lines of the wearer's panty to allow the wearer to install the flap such that the shape of the bending line of flap in the folded position conforms to the shape of the wearer's panty and have the ability to relieve stresses developed as a result of folding the flap beneath the wearer's panty.